Touch panel and method for fabricating the same and display device comprising the same

ABSTRACT

A touch panel is provided. The touch panel includes: a substrate, wherein the substrate includes a viewing region and a border region at an edge of the viewing region; a patterned transparent conductive layer formed on the substrate, wherein the patterned transparent conductive layer is formed on the viewing region and the border region, and the patterned transparent conductive layer has a touch sensitive function; and a patterned metal layer formed on the border region, wherein the patterned metal layer includes a contact region and a trace region connecting to the contact region, and at least a portion of the contact region overlaps with the patterned transparent conductive layer, wherein a shift range between the contact region and the patterned transparent conductive layer disposed on the border region adjacent to the contact region is smaller than about 150 μm.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. patentapplication Ser. No. 13/572,041, filed on Aug. 10, 2012, which claimspriority of Taiwan Patent Application No. 100129321, filed on Aug. 17,2011, the entire of which is incorporated by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to a touch panel, and in particularrelates to a touch panel and method for fabricating the same and adisplay device comprising the same.

DESCRIPTION OF THE RELATED ART

Consumer electronic applications are becoming increasingly diverse withthe rapid progress of science and technology. Many electronic productsare light, thin, short and small. Moreover, in various electronicproducts, touch panels are widely used, such as in portable electronicproducts (such as personal digital assistant (PDA) or mobile phone).

There are several types of touch panels including resistive, capacitive,surface acoustic wave, and optics touch panels, etc. The capacitive typetouch panel comprises a surface capacitive type and a projectivecapacitive type. The capacitive type touch panel has the advantage ofhigh light transmission, and considerable research attention has beenrecently focused on development thereof.

FIG. 1 shows a top-view schematic representation of a typical capacitivetouch panel 10 of prior art. The capacitive touch panel 10 comprises aborder region 2 a and a viewing region 2 b, wherein the border region 2a is formed at an edge of the viewing region 2 b. The viewing region 2 bis essentially formed by a patterned transparent conductive layer 14 a,such as indium tin oxide (ITO). The patterning process is a knownphotolithography and etching process. The border region 2 a isessentially formed by a trace 16 which is formed by a silver screenprinting process. While the manufacturing trend is towards the touchpanel to have narrow borders, an overlapping width d₁ between thepatterned transparent conductive layer 14 a and the trace 16 is neededto meet the requirement of below 0.3 mm, and a pitch d₂ between thetrace 16 and the viewing region 2 b is needed to meet the requirement ofbelow 0.5 mm.

Conventionally, the patterned transparent conductive layer 14 a isfirstly formed and then the trace 16 is formed by a silver screenprinting process. However, these fabrication processes must consider theprecision of the photolithography process and the silver screen printingprocess, and also consider the precision of assembling the cover glassand sensitive device (comprising the patterned transparent conductivelayer 14 a and the trace 16). Thus, a touch panel meeting theabove-mentioned d₁ and d₂ requirements is not easy to fabricate.

Therefore, there is a need to develop a touch panel and method forfabricating the same to improve the precision of processes andproduction capacity.

SUMMARY OF THE DISCLOSURE

The disclosure provides a touch panel, comprising: a substrate, whereinthe substrate comprises a viewing region and a border region at an edgeof the viewing region; a patterned transparent conductive layer formedon the substrate, wherein the patterned transparent conductive layer isformed on the viewing region and the border region, and the patternedtransparent conductive layer has a touch sensitive function; and apatterned metal layer formed on the border region, wherein the patternedmetal layer comprises a contact region and a trace region connecting tothe contact region, and at least a portion of the contact regionoverlaps with the patterned transparent conductive layer, and a shiftrange between the contact region and the patterned transparentconductive layer disposed on the border region adjacent to the contactregion is smaller than about 150 μm.

The invention also provides a method for fabricating a touch panel,comprising: providing a substrate, wherein the substrate comprises aviewing region and a border region at an edge of the viewing region;forming a transparent conductive layer on the substrate, wherein thetransparent conductive layer is formed on the viewing region and theborder region; forming a patterned metal layer on the border region;patterning the transparent conductive layer to form a patternedtransparent conductive layer; and defining a contact region and a traceregion connecting to the contact region from the patterned metal layer,wherein at least a portion of the contact region overlaps with thepatterned transparent conductive layer, and a shift range between thecontact region and the patterned transparent conductive layer formed onthe border region adjacent to the contact region is smaller than about150 μm.

The invention also provides a display device, comprising: a displayunit; and a touch panel formed on the display unit, wherein the touchpanel comprising: a substrate wherein the substrate comprises a viewingregion and a border region at an edge of the viewing region; a patternedtransparent conductive layer formed on the substrate, wherein thepatterned transparent conductive layer is formed on the viewing regionand the border region, and the patterned transparent conductive layerhas a touch sensitive function; and a patterned metal layer formed onthe border region, wherein the patterned metal layer comprises a contactregion and a trace region connecting to the contact region, and at leasta portion of the contact region overlaps with the patterned transparentconductive layer, wherein a shift range between the contact region andthe patterned transparent conductive layer disposed on the border regionadjacent to the contact region is smaller than about 150 μm.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a top-view schematic representation of a typical capacitivetouch panel of prior art;

FIGS. 2A-2D show schematic representations of various stages offabricating a touch panel in accordance with an embodiment of thedisclosure;

FIGS. 3A-3B show cross-sectional schematic representations of a touchpanel in accordance with an embodiment of the disclosure;

FIG. 4 show a cross-sectional schematic representation of a touch panelin accordance with another embodiment of the disclosure; and

FIG. 5 shows a cross-sectional schematic representation of a displaydevice in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The following description is of the best-contemplated mode of carryingout the disclosure. This description is made for the purpose ofillustrating the general principles of the disclosure and should not betaken in a limiting sense. The scope of the disclosure is bestdetermined by reference to the appended claims.

FIGS. 2A-2D show schematic representations of various stages offabricating a touch panel in accordance with an embodiment of thedisclosure. Firstly, referring to FIG. 2A, a substrate 102 is provided.The substrate 102 comprises a viewing region (not shown in FIG. 2A, aposition of the viewing region is like the reference number 2 b inFIG. 1) and a border region (not shown in FIG. 2A, a position of theborder region is like the reference number 2 a in FIG. 1) at an edge ofthe viewing region. The substrate 102 comprisespolyethyleneterephthalate (PET), polycarbonate (PC) orpolymethylmethacrylate (PMMA). In one embodiment, the substrate 102 isformed by polyethyleneterephthalate (PET).

Then, referring to FIG. 2B, a transparent conductive layer 104 is formedon the substrate 102, wherein the transparent conductive layer 104formed on the viewing region has a touch sensitive function. Then, apatterned metal layer 106 a is formed on the transparent conductivelayer 104 and on the border region. The patterned metal layer 106 a isformed by a screen printing process.

The transparent conductive layer 104 comprises indium tin oxide (ITO),indium zinc oxide (IZO), cadmium tin oxide (CTO), aluminum zinc oxide(AZO), indium tin zinc oxide (ITZO) zinc oxide, cadmium oxide (CdO),hafnium oxide (HfO), indium gallium zinc oxide (InGaZnO), indium galliumzinc magnesium oxide (InGaZnMgO), indium gallium magnesium oxide(InGaMgO) or indium gallium aluminum oxide (InGaAlO). The patternedmetal layer 106 a comprises copper (Cu), nickel (Ni), aluminum (Al),chromium (Cr), silver (Ag) or gold (Au).

In one embodiment, a patterned silver layer is formed on an indium tinoxide (ITO) layer by a silver screen printing process.

Next, referring to FIG. 2C, a photoresist layer 107 is formed on thepatterned metal layer 106 a.

Referring to FIG. 2D, the transparent conductive layer 104 is patternedby a series of photolithograph and etching process, including coating,exposure, developing, etching and stripping, to form a patternedtransparent conductive layer 104 a.

In prior art, the patterned metal layer is formed after the patternedtransparent conductive layer. Because the precision of the conventionalsilver screen printing process is about 150 μm (0.15 mm), a shift rangeof the patterned metal layer of prior art is at least 150 μm (0.15 mm).Compared with prior art, the patterned metal layer is formed before thepatterned transparent conductive layer, and thus the first fabricationprocess is considered as a base line. In other words, the screenprinting process having a larger error is considered as the base line.Next, the second fabrication process (photolithography and etchingprocess having a precision of about ±10 μm) is then preceded, and thusonly the shift caused by the second fabrication process is needed to beconsidered. Therefore, the shift of the overall fabrication process ofthe touch panel is decreased, and the production capacity is improved.

FIG. 3A shows a cross-sectional schematic representation of a touchpanel 300 in accordance with an embodiment of the disclosure. Thepatterned transparent conductive layer 104 a is formed on the substrate102, and the patterned metal layer 106 a is formed on the patternedtransparent conductive layer 104 a. Note that patterned metal layer 106a comprises a contact region C₁ and a trace region (not shown in FIG.3A, the trace region is like the position of the reference number 16which is not overlapped with the patterned transparent conductive layer14 a in FIG. 1) connecting to the contact region C₁, wherein the contactregion C₁ overlaps the patterned transparent conductive layer 104 a. Inother words, owing to the shift caused by the fabrication process, onlya portion of the patterned transparent conductive layer 104 a overlapsthe contact region C₁. The formation position of the contact region C₁of the patterned metal layer 106 a is represented by R and the formationposition of the patterned transparent conductive layer 104 a isrepresented by I. As shown in FIG. 3A, the formation position R isshorter than the formation position I, and a shift range between both isS₁. By the improvement of the fabrication process of the embodiment ofthe disclosure, the shift range between the formation position R and theformation position I is smaller than 150 μm, and preferably 10-150 μm.Additionally, a glue and a protective substrate (not shown in FIG. 3)are formed on the patterned metal layer 106 a, wherein the glue isformed between the patterned metal layer 106 s and the protectivesubstrate to adhere the patterned metal layer 106 s to the protectivesubstrate. The glue comprises an optic clear adhesive and the protectivesubstrate comprises a glass plate.

Referring to FIG. 3B, the formation position R of the contact region C₂of the patterned metal layer 106 a is longer than the formation positionI of the patterned transparent conductive layer 104 a, and a shift rangebetween both is S₂. By the improvement of the fabrication process of thedisclosure, the shift range between the formation position R and theformation position I is smaller than 150 μm, and preferably 10-150 μm.Note that owing to the shift caused by the second fabrication process,only a portion of the patterned metal layer 106 a overlaps the patternedtransparent conductive layer 104 a.

Furthermore, in prior art, a baking process at high temperature isproceeded after the screen printing process to dry a metal paste. Thescreen printing process and the baking process proceed after formationof the patterned transparent conductive layer, and thus the patternedtransparent conductive layer of prior art is baked at a hightemperature. During the baking process, several undesirable phenomenonsmay occur in the patterned transparent conductive layer of prior art,such as the warpage phenomenon, the bluing phenomenon or the obviousscribe line, due to non-uniform volume contraction between each of thepatterned transparent conductive layer.

Compared with prior art, the patterned metal layer 106 a is formedbefore patterning the transparent conductive layer 104, and thus thetransparent conductive layer 104, not the “patterned” transparentconductive layer 104 a, is baked by the baking process at a hightemperature. Because the transparent conductive layer 104 is notpatterned, the volume contraction of the transparent conductive layer104 is uniform, and the undesirable phenomenons (the warpage phenomenon,the bluing phenomenon or the obvious scribe line) may not occur.

Additionally, FIG. 4 shows a cross-sectional schematic representation ofa touch panel 400 in accordance with another embodiment the disclosure.A first patterned transparent conductive layer 404 a, a first patternedmetal layer 406 a, a first glue 407, a second substrate 412, a secondpatterned transparent conductive layer 414 a, a second patterned metallayer 416 a, a second glue 417 and a protective substrate 450 aresequentially formed on a first substrate 402. The first glue 407 andsecond glue 417 independently comprise an optic clear adhesive. Thefirst patterned transparent conductive layer 404 a and the secondpatterned transparent conductive layer 414 a respectively representX-axis capacitive sensor layer and Y-axis capacitive sensor layer.

Note that a shift range between a formation position of a contact regionof the first patterned metal layer 406 a and a formation position of thefirst patterned transparent conductive layer 404 a is smaller than 150μm, and preferably 10-150 μm. A shift range between a formation positionof a contact region of the second patterned metal layer 416 a and aformation position of the second patterned transparent conductive layer414 a is smaller than 150 μm, and preferably 10-150 μm.

Moreover, referring to FIG. 5, the disclosure also provides a displaydevice 500, which comprises a display unit 510 and a touch panel 400formed on the display unit 510. Note that the touch panel 400 is formedby the fabrication process of the disclosure. The display unit 510comprises a liquid crystal display (LCD) or an organic light emittingdiode (OLED).

From the above discussion, the disclosure provides a touch panel andmethod for fabricating the same. The method comprises forming thepatterned metal layer before forming the patterned transparentconductive layer. Thus, the shift range between the formation positionof the contact region of the patterned metal layer and the formationposition of the patterned transparent conductive layer is smaller than150 μm. Therefore, by changing the order of the fabrication process, thetouch panel of the disclosure meets the requirement of having a narrowborder. Additionally, the transparent conductive layer 104, not the“patterned” transparent conductive layer 104 a, is baked by the bakingprocess. Thus, the volume contraction of the transparent conductivelayer 104 is uniform, and the undesirable phenomenons (the warpagephenomenon, the bluing phenomenon or the obvious scribe line) may notoccur.

While the disclosure has been described by way of example and in termsof the preferred embodiments, it is to be understood that the disclosureis not limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A touch panel, comprising: a substrate, whereinthe substrate comprises a viewing region and a border region beside anedge of the viewing region; a patterned transparent conductive layerdisposed on the substrate, wherein the patterned transparent conductivelayer is disposed on the viewing region and the border regionrespectively, and the patterned transparent conductive layer has a touchsensitive function; and a patterned metal layer disposed on the borderregion, wherein the patterned metal layer comprises a contact region anda trace region connecting the contact region, and at least a portion ofthe contact region overlaps the patterned transparent conductive layer,wherein a shift range between the contact region and the patternedtransparent conductive layer disposed on the border region is smallerthan about 150 μm.
 2. The touch panel as claimed in claim 1, wherein theshift range between the contact region and the patterned transparentconductive layer disposed on the border region is about 10-150 μm. 3.The touch panel as claimed in claim 1, wherein the substrate comprisespolyethyleneterephthalate (PET), polycarbonate (PC) orpolymethylmethacrylate (PMMA).
 4. The touch panel as claimed in claim 1,wherein the patterned transparent conductive layer comprises indium tinoxide (ITO), indium zinc oxide (IZO), cadmium tin oxide (CTO), aluminumzinc oxide (AZO), indium tin zinc oxide (ITZO) zinc oxide, cadmium oxide(CdO), hafnium oxide (HfO), indium gallium zinc oxide (InGaZnO), indiumgallium zinc magnesium oxide (InGaZnMgO), indium gallium magnesium oxide(InGaMgO) or indium gallium aluminum oxide (InGaAlO).
 5. The touch panelas claimed in claim 1, wherein the patterned metal layer comprisescopper (Cu), nickel (Ni), aluminum (Al), chromium (Cr), silver (Ag) orgold (Au).
 6. The touch panel as claimed in claim 1, further comprising:a protective substrate formed on the substrate; and a glue formedbetween the substrate and the protective substrate to adhere thesubstrate to the protective substrate.
 7. The touch panel as claimed inclaim 6, wherein the glue comprises an optic clear adhesive and theprotective substrate comprises a glass plate.
 8. The touch panel asclaimed in claim 1, further comprising: a first glue formed on thesubstrate; a second substrate formed on the first glue; a secondpatterned transparent conductive layer disposed on the second substrate;a second patterned metal layer overlaps with an edge of the secondpatterned transparent conductive layer, wherein the second patternedmetal layer comprises a second contact region and a second trace regionconnecting the second contact region, and at least a portion of thesecond contact region overlaps the second patterned transparentconductive layer, and a shift range between the second contact regionand the second patterned transparent conductive layer is smaller thanabout 150 □m; a second glue formed on the second substrate; and aprotective substrate formed on the second glue.
 9. The touch panel asclaimed in claim 1, wherein the contact region comprises a first edgeand the patterned transparent conductive layer comprises a second edgeadjacent to the first edge, wherein the shift range is a distancebetween the first edge and the second edge.
 10. A display device,comprising: a display unit; and a touch panel disposed on the displayunit, wherein the touch panel comprising: a substrate, wherein thesubstrate comprises a viewing region and a border region beside an edgeof the viewing region; a patterned transparent conductive layer disposedon the substrate, wherein the patterned transparent conductive layer isdisposed on the viewing region and the border region respectively, andthe patterned transparent conductive layer has a touch sensitivefunction; and a patterned metal layer disposed on the border region,wherein the patterned metal layer comprises a contact region and a traceregion connecting the contact region, and at least a portion of thecontact region overlaps the patterned transparent conductive layer,wherein the contact region comprises a first edge and the patternedtransparent conductive layer comprises a second edge adjacent to thefirst edge, wherein a distance between the first edge and the secondedge is smaller than about 150 μm.
 11. The display device as claimed inclaim 10, wherein the display unit comprises a liquid crystal display(LCD) or an organic light emitting diode (OLED).
 12. A method forfabricating a touch panel, comprising: providing a substrate, whereinthe substrate comprises a viewing region and a border region beside anedge of the viewing region; forming a transparent conductive layer onthe substrate, wherein the transparent conductive layer is disposed onthe viewing region and the border region respectively; forming apatterned metal layer on the border region, wherein the patterned metallayer comprises a contact region and a trace region connecting thecontact region; patterning the transparent conductive layer to form apatterned transparent conductive layer; and wherein at least a portionof the contact region overlaps with the patterned transparent conductivelayer, and a shift range between the contact region and the patternedtransparent conductive layer disposed on the border region is smallerthan about 150 μm.
 13. The method for fabricating a touch panel asclaimed in claim 12, wherein the patterned transparent conductive layerdisposed on the viewing region has a touch sensitive function.
 14. Themethod for fabricating a touch panel as claimed in claim 12, wherein thepatterned metal layer is formed on the border region by a screenprinting process.
 15. The method for fabricating a touch panel asclaimed in claim 12, wherein the patterned transparent conductive layeris formed by a photolithograph and etching process.
 16. The method forfabricating a touch panel as claimed in claim 12, wherein the shiftrange between the contact region and the patterned transparentconductive layer disposed on the border region is about 10-150 μm. 17.The method for fabricating a touch panel as claimed in claim 12, whereinthe contact region comprises a first edge and the patterned transparentconductive layer comprises a second edge adjacent to the first edge,wherein the shift range is a distance between the first edge and thesecond edge.